1. Field of the Invention
Field of the invention relates to an electrode structure for measuring a biosignal from a living body, which electrode structure comprises a contact surface intended to be placed against the body.
2. Brief Description of the Related Art
The invention is particularly applied in a non-invasively measuring, personal heart rate measuring arrangement, in an electrode belt, or a so-called transmitter belt, of the heart rate measuring arrangement, the belt being in a wireless connection with a receiver unit, in most cases a wristband unit. The electrode belt need not necessarily be a transmitter, but it may just be a measuring unit as well, if it is equipped with a display or a memory, for example.
In known electrode structures of electrode belts, there are long continuous protrusions next to each other on the contact surface, and they are either direct or they wind in the direction of the surface. In both known electrode structures, each protrusion is long, continuous and equally thick.
The known solutions are associated with drawbacks concerning particularly the quality of the contact caused by the electrode against the skin. Since a protrusion is continuous, each continuous protrusion only creates one long contact surface, and the contact between the long continuous protrusion and the skin is not especially strong. It is obvious that a weak contact between the surface of the electrode structure and the skin may lead to errors in the measurement results.
The object of the invention is thus to provide a new electrode structure avoiding the problems and drawbacks associated with the known solutions.
To achieve the above object, the electrode structure of the invention is characterized in that the contact surface comprises several adjacent wave fronts, which wave fronts comprise protrusions and valleys, which are situated lower between the protrusions.
The invention is based on the idea that an electrode surface is shaped in a way that improves the quality of the contact between the surface of the electrode structure and the skin.
The electrode structure of the invention provides the advantage that the contact between the electrode surface and the skin improves. The invention provides a large number of contact points with small surface areas for use, each of which contact points effects a stronger point contact. By means of a better contact, reliable measurement results free of interference can be achieved. The preferred embodiments of the invention and other embodiments described later in greater detail make the advantages of the invention more significant. Proceeding wavelike and comprising at least to some extent curved protrusions and valleys, each wave front and thus the entity of several wave fronts feel good against the skin and are easier to keep clean as well, since the protrusions change slowly into valleys and vice versa.